Work roll changers

ABSTRACT

In a rolling mill the improvement of a roll changer for rapidly changing from one set of work rolls to another automatically. The work rolls (and chocks) are raised and lowered on spaced apart first inside rails contacting the chocks supporting the upper work roll from operating position to transfer position in the mill housing spaced from each other so that they independently seek a predetermined drive position, preferably by the balancing means of the rolling mill. The work rolls are removed from and inserted into the rolling mill through windows in the mill housing on spaced apart first inside rails and second outside rails by a guide means and latch means positioned on a transfer bed and shift car positioned adjacent the rolling mill without the uses of additional power means to connect and disconnect the latch means to and from the work rolls. The transfer bed may be movable to raise and lower the work rolls from floor level to transfer level.

United States Patent Eibe et al. Oct. 24, 1972 54] WORK ROLL CHANGERs Primary Examiner-Charles w. Lanham Assistant Examiner-Michael J. Keenan [72] l f 'z z y'gr ly fg Attorney-Smith, Harding, Barley & Follmer rell, Robinson Twp., Allegheny [57] ABSTRACT County, Pa. I u l t n a rolling mi the improvement of a r0 1 changer for [73] Asslgnee' Bhw'Kmx Company rapidly changing from one set of work rolls to another 22 i N 30, 1970 automatically. The work rolls (and checks) are raised and lowered on spaced apart first inside rails contact- [21] Appl. 93,727 ing the checks supporting the upper work roll from operating position to transfer position in the mill hous- {521 US. Cl ..72/239 ing Spaced fnn1 i miner W they independently seek a predetermined drive position, preferably by the [51] Int. Cl. ..B21b 31/08 balancing means of the rolling mill The work rolls are [58] Field of Search ..72/237, 238, 239 removed from and inserted into the g mi through windows in the mill housing on spaced apart [56] References Clted first-inside rails and second outside rails by a guide UNITED STATES PATENTS means and latch means positioned on a transfer bed and shift car positioned ad acent the rolling mill 3,504,517 Clement without the uses of power means to connect 3,566,498 3/1971 Kato et 81. ..72/239 and disconnect the latch means to and from the work 3,208,260 9/ 1965 Sieger et al. ..72/239 rolls, The transfer bed may be movable to raise and 3,593,554 7/1971 Swift ..72/238 lower the work rolls from floor level to transfer level.

749,745 1/1904 Von Philip ..72/239 2,037,210 4/1936 Buente ..72/239 18 Cnnms, 9 e

FOREIGN PATENTS OR APPLICATIONS 946,427 I/ 1964 Great Britain ..72/239 P'A'T ENTED um 24 1912 SHEEI 1 0F 8 P'A'TE'NT'ED um 24 1972 SHEET 3 0F 8 I f f I r I r a r r 4 v a! INVENTORS Werner W. Eibe 8 Wilfred T. Farrell Jr.

v a w a v a r n I w a 4 PATENTEDUU24 I912 7 3,699,796

sum u or. 8

INVENTORS Werner W. Eibe 8 Wilfred T. Farrell Jr.

PATENTEDUBT 24 I972 SHEET 5 [IF 8 Fig .5.

INVENTORS Werner W. Ei'be 8 BY Wilfred T. Farrell Jr.

PA TENTEU BI I912 9.999.799

sum 6 or 8 INVENTORS Werne r W. Eibe 6 BY Wilfred T. Farrell Jr.

PATEN TEDnm 24 I972 3.699.796

sum 7 BF 8 INVENTORS Werner W. Eibe 8:

BY Wilfred T. Forrell Jr. 5 f m PATENTED BT 9 9.999.799

SHEET 8 [1F 8 INVENTORS Werner W. Eibe 9 BY Wilfred T. Farrell Jr. 74,6 a?

WORK ROLL CHANGERS This invention relates to apparatus for automatically changing the work rolls of a rolling mill. It provides a relatively simple and relatively inexpensive apparatus for rapidly changing the work rolls of a rolling mill automatically.

A rolling mill is used to make metals into various shapes. It may consist of relatively small work rolls and larger back-up rolls positioned parallel to each other and in contact with work rolls when the mill is operating. The work rolls are held in position by chocks at each end of the mill engaging the necks of the rolls. The chocks are in turn positioned within windows in the ends of the mill housing so that chocks can move perpendicular to the movement of the material through the mill and be loaded during mill operation by screwdowns. The screwdowns engage the chocks that position the upper back-up roll during operation and also may raise and lower it into operating position. Balancing means are provided for controlling the bite of the rolling mill during operation and for raising and lowering the work rolls.

The changing of the work rolls of the roll mill has been of utmost importance to the efficient operation of the modern steel mill. It is frequently necessary to change work rolls each shift or even midway between shifts because of changes in the composition and dimensions of the steel needed. In the past, work rolls were changed by overhead cranes using counterweighted yokes or cradles for individually moving a work roll into and out of a rolling mill housing. Such apparatus was excessively wasteful of time and manpower; with modern high speed mills, often more time could be spent in changing work rolls than in actual rolling operation.

Many proposals have been made to eliminate this lost time and expense with more or less success. But all such proposals known to us have lacked the efficiency and flexibility which high speed mills require in order to take full advantage of their production potential. In addition, such proposals were expensive and complex to build and operate. For example, such proposals may have required separate drive means to raise and lower the work rolls and chocks from operating position to change position, the manual disengagement of the power means for the balancing means, and/or separate drive means for engaging and disengaging the latch mechanism used to insert and remove the work rolls (and chocks) from the rolling mill. 7

Our invention overcomes these disadvantages and difficulties and provides a simpler and less expensive apparatus for rapidly and automatically changing the work rolls of a rolling mill.

Our invention is directed to a rolling mill having upper and lower work rolls forming a pass line and a mill housing surrounding said pass line. Windows are provided in each end of said mill housing on opposite sides of the pass line, each window receiving a pair of superimposed roll chocks, i.e., upper and lower roll chocks. The upper and lower work rolls have neck portions which are journaled into said roll chocks and are positioned by balancing means to adjust the bite of the rolling mill.

In said rolling mill we provide the improvement comprising a pair of spaced apart first inside rails positioned in said windows and extending from one end of mill housing to the other end, said first inside rails contacting said upper roll chocks; first driving means for raising and lowering said first inside rails and in turn said upper work rolls; vertical support means rigidly attached to said upper roll chocks and slidably attached to said lower roll chocks, and stop means adjacent said vertical support means for raising and lowering said lower work rolls spaced from said upper work roll as said first rails are raised and lowered; transport means, preferably wheel means fastened to portions of said vertical support means, are adapted to carry said upper and lower work rolls (and chocks) without the mill housing spaced from one another. Preferably said first driving means is also the balancing means for said rolling mill.

Preferably a roll transfer bed is positioned to one side of said rolling mill, and preferably can be raised and lowered by second drive means. A shift car is positioned on said transfer bed and is movable substantially parallel to the pass line of said rolling mill. Third drive means are provided on said transfer bed for moving said shift car substantially parallel to the pass line of said rolling mill. At least two pairs of spaced apart second outside rails are positioned on said shift car, each pair of second outside rails being adapted for selective horizontal alignment with said transport means. Guide means are positioned on said transfer bed and said shift car adjacent each pair of second outside rails. Latch means are positioned on said roll transfer bed in permanent alignment with work rolls when positioned in said mill housing, and are adapted to move along said guide means. Said latch means move said work rolls and said roll chocks into and out of said mill housing on said first and second rails by use of fourth drive means which moves said latch means along said guide means. Said latch means are also adapted to engage a work roll without the use of additional drive or power means.

Other details, objects and advantages of our invention will become apparent as the following description of the present preferred embodiments thereof proceeds.

In the accompanying drawings we illustrate the presently preferred embodiments of our invention in which:

FIG. 1 is a top plan view of a rolling mill stand and roll changer;

FIG. 2 is a partial cross-sectional view taken along line II--II of FIG. 1 showing the roll changer in lowered position;

FIG. 3 is a partial cross-sectional view taken along line II-II of FIG. 1 showing the roll changer in raised position;

FIG. 4 is a partial side view of an alternative rolling mill stand and roll changer;

FIG. 5 is a partial end view of the rolling mill stand and roll changer shown in FIG. 4;

FIG. 6 is an enlarged fragmentary cross section on line VI-VI of FIG. 1 showing the latch means of the roll changer in position to withdraw old work rolls from the mill housing;

FIG. 7 is an enlarged fragmentary cross section on line VI-VI of FIG. 1 showing the latch means of the roll changer positioning new work rolls in the mill hous FIG. 8 is a partial side view of a second alternative rolling mill stand and roll changer; and

FIG. 9 is a partial end view of the second alternative rolling mill stand and roll changer shown in FIG. 8.

Referring to the drawings, we illustrate a rolling mill 10 having upper work roll 11 and lower work roll 12 forming a pass line 10A. Rolling mill 10 has a mill housing 13 surrounding said pass line 10A. Mill housing 13 has windows 14 in each end of it. Upper roll chocks l and lower roll chocks 16 support upper work roll 11 and lower work roll 12 respectively and are positioned in said windows 14. Back-up rolls 17 are positioned above and below upper and lower work rolls 11 and 12 and in contact with them when the rolling mill is ready for operation. Back-up rolls 17 are journaled into the ends of the mill housing 13. Back-up roll 17 in contact with upper work roll 11 is loaded by screwdowns (not shown) which are conventional on rolling mills.

A pair of spaced apart first inside rails 18 are positioned in said windows 14 and extend from one end of the mill housing 13 to the other end. Said first inside rails 18 are positioned in contact with upper work roll chocks at 19. First drive means 19A, a hydraulic means, is provided in mill housing 13 for raising and lowering said first inside rails 18 and in turn said upper work roll 12. First drive means 19A also serves as a chock balancing means to adjust the bite of rolling mill 10. Four vertical support means extend through and are rigidly attached to said upper roll chocks l5, and extend through and are slidably attached to said lower work chocks 16. Vertical support means 20 are provided with stop means 21 so that said lower work roll 12 can be raised or lowered spaced from said upper work roll 11 as said upper work roll 11 is raised or lowered on first inside rails 18.

Wheel means 22 are fastened to lower portions of said vertical support means 20 and are adapted to carry work rolls 11 and 12 (and roll chocks 15 and 16) with out mill housing 13. When the work rolls 11 and 12 are with in the rolling mill 10, the wheel means 22 are suspended in windows 14 of mill housing 13 when first rails 18 are in raised position, and positioned in seats 23 in mill housing 13 when first rails 18 are in lowered position. Slotted stop means 21A are positioned on at least one of said first inside rails 18 to vertically align said wheel means 22 with second outside rails 28 and 28 when first rails 18 are raised to their highest position.

Roll'transfer bed 24 is positioned to one side of rolling mill 10. Preferably roll transfer bed 24 is provided (as shown in the alternative embodiments) with second drive means 25 for raising and lowering work rolls 11 and 12 (and roll chocks l5 and 16) from floor level to transfer level. Second drive means 25 for raising and lowering can be hydraulic means as shown in FIGS. 4 and 5, or can be mechanical means such as screw jacks as sho'wn in FIGS. 8 and 9. Alternatively, roll transfer bed 24 may not have second drive means 25 for raising and lowering (as shown in FIG. 1) where the distance between pass line 10A and the floor level is relatively small or where space will permit the presence of a large transfer bed adjacent the rolling mill 10. In this connection, the roll transfer bed 24 may be stationary; or movable'on wheel means 24A and rails 248 by drive means 24C, and positioned adjacent rolling mill 10 by fastening means 24D attaching transfer bed 24 to mill housing 13. In any case, the roll transfer bed 24 has positioned on it a shift car 26 which is movable substantially parallel to pass line 10A of said rolling mill 10. The roll transfer bed 24 also supports third drive means 27, a hydraulic means, for moving said shift car 26 substantially parallel to the pass line 10A of said rolling mill 10.

In addition, two pairs of spaced apart second outside rails 28 and 28' are positioned on said shift car 26 and are adapted to selectively horizontally align with wheel means 22 as suspended in the windows 14 of mill housing 13 in in the highest position. Guide means 29 and 29' are positioned on said shift car 26 between each pair of second outside rails 28 and 28 respectively. Latch means 30 are positioned on said roll transfer bed 24 in permanent alignment with the neck 31 of a lower work roll 12 as supported in the mill housing 13 with first inside rails 18 in highest position. Latch means 30 are adapted to move along said guide means 29 and 29 on said shift car 26 when they are aligned with mill housing 13, adapted to engage with and disengage from neck 31 of lower work roll 12 without the use of separate drive or power means, and to move work rolls 12 and 11 (and chocks 15 and 16) into and out of mill housing 13 on first inside rails 18 and second outside rails 28. Fourth drive means 32 are provided on roll transfer bed 24 for driving latch means 30 along guide means 29 and in turn moving said work rolls 11 and 12 into and out of said mill housing 13.

Preferably latch means 30 has a spring means 33 and a latch finger 34 rotatably movable about pivot 35. Also the one guide means 29' has a curved end portion 36 adjacent mill housing 13 and the other guide means 29 has a straight end portion 38 adjacent mill housing 13. By this arrangement, latch means 30 can engage neck 31 of lower work roll 12 by moving latch finger 34 into grove 37 in neck 31 against spring means 33 while latch means 30 moves along straight end portion 38 adjacent mill housing 13. And said latch means 30 can disengage from neck 31 of lower work roll 12 by disconnecting latch finger 34 from groove 37 while latch 30 moves along curved end portion 36 adjacent mill housing 13. By the arrangement, the latch means 30 can automatically connect with and disconnect from the neck 31 of lower work roll 12 without the use of ad ditional drive or power means.

Said fourth drive means 32 for moving latch 30 along guide means 29 or 29' can be of any suitable and convenient form. It can, for example, be a push rod means moved by a hydraulic cylinder (not shown). But preferably fourth drive means 32 is comprised of pivoted chain'like lengths 39 which have moving means 40 attached to each pivot 41 thereof which are adapted to slide or roll 'within said guide means 29 forming a push-pull chain assembly. The push-pull chain assembly can be driven along said guide means by a sprocket and reversible motor assembly 32A.

Guide means 29 and 29 can also be of any suitable and convenient form. We prefer, however, that guide means 29 be comprised of spaced apart channels 42 opening toward each other to form a track. In this way, the latch means 30 can be moved along guide means 29 or 29' by simply providing rollers 43 on a latch means 30 that are adapted to roll within channels 42. Also moving means 40 can be simply rollers similar to rollers 43 to roll within channels 42.

In operation, our roll changer can rapidly change work rolls 11 and 12 (and roll chocks 15 and 16) for different work rolls 11' and 12' (and roll chocks 15 and 16) automatically. This is done by first positioning work rolls 11' and 12' on roll transfer bed 24 on second outside rails 28' at floor level and raising roll transfer bed 24 to transfer level by second drive means 25. The rolling mill is stopped and back-up roll 17 in contact with upper work roll 11 is raised. The work rolls 1 1 and 12 (and roll chocks and 16) are raised in unison spaced from each other by first drive means 19, first rails 18, vertical support means 20 and stop means 21 until first inside rails 18 are stopped in their highest position by stop means 21A. In this position the wheel means 22 are vertically aligned with second outside rails 28 and 28'.

Empty second rails 28 are selectively horizontally aligned with wheel means 22 by movement of the shift car 26 on the roll transfer bed 24 parallel to pass line 10A by third drive means 27. Latch means are then moved along guide means 29 by fourth drive means 32 until it engages the neck 31 of lower work roll 12. Latch means 30 is reversed and moved along a guide means 29 between the empty pair of second outside rails 28, in turn moving the work rolls l1 and 12 out of the mill housing 13 onto the pair of empty second outside rails 28.

The shift car 26 is thereafter moved to selectively horizontally a ign the second outside rails 28 supporting the work rolls 11' and 12 (and roll chocks 15 and 16) with the mill housing 13. Latch means 30 is thereby also aligned with a guide means 29' between said second outside rails 28'. Latch means 30 is then moved along guide means 29' between second outside rails 28' moving said work rolls 11 and 12 into mill housing 13 until latch means 30 disengages from neck 31 of lower work roll 12' by use of curved end portion 36 of guide means 29. Latch means 30 is thereafter retracted for subsequent use in roll changing.

The pair of work rolls 11' and 12' are then lowered into operating position on first inside rails 18 by first drive means 19 spaced from one another. In this way, the work rolls 11' and 12' can independently seek a predetermined work position.

Rolling mill 10 can thereafter continue operation. And the roll transfer bed 24 lowered to floor level and work rolls l1 and 12 rolled away for repair or storage for subsequent use.

While we have illustrated and described certain present preferred embodiments of our invention, it is to be understood that we do not limit ourselves thereto and that our invention may be otherwise variously practiced within the scope of the following claims.

We claim:

1. In a rolling mill having upper and lower work rolls forming a pass line, a mill housing surrounding said pass line, a window in each end of said housing, upper and lower roll chocks positioned in each said window and adapted to support said upper and lower work rolls respectively: a pair of spaced apart first inside rails positioned in said windows and extending from one end of said mill housing to the other end, said first inside rails contacting said upper roll chocks; first drive means for raising and lowering said first rails and in turn said upper work roll; vertical support means rigidly attached to said upper roll chocks and slidably attached to said lower roll chocks, and stop means on said vertical support means for raising and lowering said lower work roll spaced from said upper work roll as said first inside rails and upper work rolls are raised and lowered; transport means fastened to portions of said vertical support means and adapted to carry said work rolls with out the mill housing; a roll transfer bed positioned to one side of said rolling mill; second drive means for raising and lowering said roll transfer bed; a shift car positioned on said transfer bed and moveable substantially parallel to the pass line of said rolling mill, at least two pairs of spaced apart second outside rails positioned on said shift car, each pair of second outside rails adapted for selective alignment with said transport means; third drive means for moving said shift car substantially parallel to the pass line of said rolling mill and selectively align said second outside rails; guide means positioned on said transfer bed and said shift car adjacent each pair of second outside rails; latch means positioned on said roll transfer bed in permanent alignment with work rolls positioned in said mill housing, adapted to move along said guide means, adapted to engage and disengage a work roll without additional drive means, and move said work rolls and said roll chocks into and out of said mill housing on said first inside rails and second outside rails; and fourth drive means for moving said latch means along said guide means.

2. A rolling mill apparatus as claimed in claim 1 wherein: one said guide means has a straight end portion adjacent said mill housing; said latch means has a spring means and a pivoted latch finger for engaging neck portions of a work roll against said spring means as said latch means is moved along a straight end portion of one said guide means adjacent said mill housing; and another said guide means has a curved end portion adjacent said mill housing for disengaging said pivoted latch finger as said latch means is moved along said curved portion of said guide means adjacent said rolling mill.

3. A rolling mill apparatus as claimed in claim 1 wherein: said fourth drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths adapted to be slidably moved in said guide means.

4. A rolling mill apparatus as claimed in claim 1 wherein: each said guide means is comprised of spaced apart channels opening toward each other to form a track; said latch means has roller means engaging said spaced apart channels; and said fourth drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths and roller means positioned at end portions of said pivoted lengths adapted slidably to move on said guide means.

5. A rollihg mill apparatus as claimed in claim 1 wherein: said fourth drive means for moving said latch means along said guide means is comprised of a pullrod means.

6. A rolling mill apparatus as claimed in claim 5 wherein: said pull-rod means includes a piston movable in a hydraulic cylinder.

7. In a rolling mill having upper and lower work rolls forming a pass line, a mill housing surrounding said pass line, a window in each end of said housing, upper and lower roll chocks positioned in each said window and adapted to support said upper and lower work rolls respectively: a pair of spaced apart first inside rails positioned in said windows and extending from one end of said mill housing to the other end, said first inside rails contacting said upper roll chocks; first drive means for raising and lowering said first inside rails and in turn said upper work roll; a vertical support means rigidly attached to said upper roll chocks and slidably attached to said lower roll chocks, and stop means on said vertical support means for raising and lowering said lower work roll spaced from said upper work roll as said first inside rails and upper work rolls are raised and lowered; transport means adapted to support said work rolls and said roll chocks with out said mill housing, a roll transfer bed positioned to one side of said rolling mill and adapted to carry said transport means with out said mill housing.

8. A rolling mill apparatus as claimed in claim 7 wherein: said transport means is comprised of wheel means fastened to portions of said support means.

9. A rolling mill apparatus as claimed in claim 7 comprising in addition: at leastone pair of spaced apart second outside rails positioned on said transfer bed; guide means positioned on said transfer bed and adjacent each pair of second rails; latch means permanently aligned with saidwork rolls in said mill housing positioned to move on said guide means, and adapted to engage a work roll and move said work rolls and said roll chocks into and out of said mill housing on said first inside rails and second outside rails; and fourth drive means for moving said latch means along said guide means.

10. A rolling mill apparatus as claimed in claim 7 comprising in addition: second drive means for raising and lowering said roll transfer bed.

11. A rolling mill apparatus as claimed in claim 9 wherein: one said guide means has a straight end portion adjacent said mill housing; said latch means has a spring means and a pivoted latch finger for engaging neck portions of a work roll against said spring means as said latch means is moved along a straight end portion of one said guide means adjacent said mill housing; and another said guide means has a curved portion for disengaging said pivoted latch finger as said latch means is moved along said curved portion of said guide means adjacent said rolling mill.

12. A rolling mill apparatus as claimed in claim 11 wherein: said drive means for moving said latch means along said guide means is comprised of pivoted chainlike lengths adapted to be slidably moved in said guide means.

13. A rolling mill apparatus as claimed in claim 11 wherein: each said guide means is comprised of spaced apart channels opening toward each other to form a track; said latch means has roller means engaging said spaced apart channels; and said drive means for moving said rolling millgat least two pairs of spaced apart second rai s positioned on said shift car, each pair of second outside rails adapted for selective alignment with transport means for transporting work rolls into and out of said rolling mill; drive means for moving said shift car substantially parallel to the pass line of said rolling mill; guide means positioned on said transfer bed and said shift car adjacent each pair of second outside rails, one said guide means having a straight end portion adjacent said rolling mill and another said guide means having a curved end portion adjacent said rolling mill; latch means positioned on said roll transfer bed in permanent alignment with work rolls positioned in said mill housing adapted to move along said guide means, and move work rolls into and out of said mill housing on said second outside rails, said latch means having a spring means and a pivoted latch finger for engaging a work roll against said spring means as said guide means moves along said straight portion of said guide means adjacent said roll mill and for disengaging said pivoted latch finger as said latch means moves along said curved portion of said guide means adjacent said rolling mill.

15. A rolling mill work roll changing apparatus as claimed in claim 14 wherein: said drive means for moving said latch means along said guide means is comprised of pivoted chain like lengths adapted to be slidably moved on said guide means.

16. A rolling mill work roll changing apparatus as claimed in claim 14 wherein: each said guide means is comprised of spaced apart channels opening toward each other to form a track, said latch means has roller means engaging said spaced apart channels; and said drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths and roller means positioned at end portions of said pivoted lengths and adapted to slidably move in said guide means.

17. A rolling mill apparatus as claimed in claim 1 wherein said first drive means is constructed and arranged to act as the work roll balancing cylinders for the rolling mill.

18. A rolling mill apparatus as claimed in claim 1 wherein said vertical support means comprises stilt-like members secured at their upper ends on said upper roll chocks and extending downwardly therefrom through openings in said lower roll chocks whereat said transport means are fastened thereto. 

1. In a rolling mill having upper and lower work rolls forming a pass line, a mill housing surrounding said pass line, a window in each end of said housing, upper and lower roll chocks positioned in each said window and adapted to support said upper and lower work rolls respectively: a pair of spaced apart first inside rails positioned in said windows and extending from one end of said mill housing to the other end, said first inside rails contacting said upper roll chocks; first drive means for raising and lowering said first rails and in turn said upper work roll; vertical support means rigidly attached to said upper roll chocks and slidably attached to said lower roll chocks, and stop means on said vertical support means for raising and lowering said lower work roll spaced from said upper work roll as said first inside rails and upper work rolls are raised and lowered; transport means fastened to portions of said vertical support means and adapted to carry said work rolls with out the mill housing; a roll transfer bed positioned to one side of said rolling mill; second drive means for raising and lowering said roll transfer bed; a shift car positioned on said transfer bed and moveable substantially parallel to the pass line of said rolling mill, at least two pairs of spaced apart second outside rails positioned on said shift car, each pair of second outside rails adapted for selective alignment with said transport means; third drive means for moving said shift car substantially parallel to the pass line of said rolling mill and selectively align said second outside rails; guide means positioned on said transfer bed and said shift car adjacent each pair of second outside rails; latch means positioned on said roll transfer bed in permanent alignment with work rolls positioned in said mill housing, adapted to move along said guide means, adapted to engage and disengage a work roll without additional drive means, and move said work rolls and said roll chocks into and out of said mill housing on said first inside rails and second outside rails; and fourth drive means for moving said latch means along said guide means.
 2. A rolling mill apparatus as claimed in claim 1 wherein: one said guide means has a straight end portion adjacent said mill housing; said latch means has a spring means and a pivoted latch finger for engaging neck portions of a work roll against said spring means as said latch means is moved along a straight end portion of one said guide means adjacent said mill housing; and another said guide means has a curved end portion adjacent said mill housing for disengaging said pivoted latch finger as said latch means is moved along said curved portion of said guide means adjacent said rolling mill.
 3. A rolling mill apparatus as claimed in claim 1 wherein: said fourth drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths adapted to be slidably moved in said guide means.
 4. A rolling mill apparatus as claimed in claim 1 wherein: each said guide means is comprised of spaced apart channels opening toward each other to form a track; said latch means has roller means engaging said spaced apart channels; and said fourth drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths and roller means positioned at end portions of said pivoted lengths adapted slidably to move on said guide means.
 5. A rolling mill apparatus as claimed in claim 1 wherein: said fourth drive means for moving said latch means along said guide means is comprised of a pull-rod means.
 6. A rolling mill apparatus as claimed in claim 5 wherein: said pull-rod means includes a piston movable in a hydraulic cylinder.
 7. In a rolling mill having upper and lower work rolls forming a pass line, a mill housing surrounding said pass line, a window in each end of said housing, upper and lower roll chocks positioned in each said window and adapted to support said upper and lower work rolls respectively: a pair of spaced apart first inside rails positioned in said windows and extending from one end of said mill housing to the other end, said first inside rails contacting said upper roll chocks; first drive means for raising and lowering said first inside rails and in turn said upper work roll; a vertical support means rigidly attached to said upper roll chocks and slidably attached to said lower roll chocks, and stop means on said vertical support means for raising and lowering said lower work roll spaced from said upper work roll as said first inside rails and upper work rolls are raised and lowered; transport means adapted to support said work rolls and said roll chocks with out said mill housing, a roll transfer bed positioned to one side of said rolling mill and adapted to carry said transport means with out said mill housing.
 8. A rolling mill apparatus as claimed in claim 7 wherein: said transport means is comprised of wheel means fastened to portions of said support means.
 9. A rolling mill apparatus as claimed in claim 7 comprising in addition: at least one pair of spaced apart second outside rails positioned on said transfer bed; guide means positioned on said transfer bed and adjacent each pair of second rails; latch means permanently aligned with said work rolls in said mill housing positioned to move on said guide means, and adapted to engage a work roll and move said work rolls and said roll chocks into and out of said mill housing on said first inside rails and second outside rails; and fourth drive means for moving said latch means along said guide means.
 10. A rolling mill apparatus as claimed in claim 7 comprising in addition: second drive means for raising and lowering said roll transfer bed.
 11. A rolling mill apparatus as claimed in claim 9 wherein: one said guide means has a straight end portion adjacent said mill housing; said latch means has a spring means and a pivoted latch finger for engaging neck portions of a work roll againsT said spring means as said latch means is moved along a straight end portion of one said guide means adjacent said mill housing; and another said guide means has a curved portion for disengaging said pivoted latch finger as said latch means is moved along said curved portion of said guide means adjacent said rolling mill.
 12. A rolling mill apparatus as claimed in claim 11 wherein: said drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths adapted to be slidably moved in said guide means.
 13. A rolling mill apparatus as claimed in claim 11 wherein: each said guide means is comprised of spaced apart channels opening toward each other to form a track; said latch means has roller means engaging said spaced apart channels; and said drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths and roller means positioned at end portions of said pivoted lengths and adapted to slidably move in said guide means.
 14. A rolling mill work roll changing apparatus comprising: a roll transfer bed positioned to one side of a rolling mill; a shift car positioned on said transfer bed and moveable substantially parallel to the pass line of said rolling mill; at least two pairs of spaced apart second rails positioned on said shift car, each pair of second outside rails adapted for selective alignment with transport means for transporting work rolls into and out of said rolling mill; drive means for moving said shift car substantially parallel to the pass line of said rolling mill; guide means positioned on said transfer bed and said shift car adjacent each pair of second outside rails, one said guide means having a straight end portion adjacent said rolling mill and another said guide means having a curved end portion adjacent said rolling mill; latch means positioned on said roll transfer bed in permanent alignment with work rolls positioned in said mill housing adapted to move along said guide means, and move work rolls into and out of said mill housing on said second outside rails, said latch means having a spring means and a pivoted latch finger for engaging a work roll against said spring means as said guide means moves along said straight portion of said guide means adjacent said roll mill and for disengaging said pivoted latch finger as said latch means moves along said curved portion of said guide means adjacent said rolling mill.
 15. A rolling mill work roll changing apparatus as claimed in claim 14 wherein: said drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths adapted to be slidably moved on said guide means.
 16. A rolling mill work roll changing apparatus as claimed in claim 14 wherein: each said guide means is comprised of spaced apart channels opening toward each other to form a track; said latch means has roller means engaging said spaced apart channels; and said drive means for moving said latch means along said guide means is comprised of pivoted chain-like lengths and roller means positioned at end portions of said pivoted lengths and adapted to slidably move in said guide means.
 17. A rolling mill apparatus as claimed in claim 1 wherein said first drive means is constructed and arranged to act as the work roll balancing cylinders for the rolling mill.
 18. A rolling mill apparatus as claimed in claim 1 wherein said vertical support means comprises stilt-like members secured at their upper ends on said upper roll chocks and extending downwardly therefrom through openings in said lower roll chocks whereat said transport means are fastened thereto. 